Photographing system, calibration method, and non-transitory computer-readable medium storing program

Abstract

A photographing system according to one example embodiment includes a hardware photographing device configured to photograph each of a first pattern and a second pattern; at least one memory storing instructions; and at least one processor configured to execute the instructions to: set, for the hardware photographing device, a control value for changing the focal position; evaluate degrees of focus of a plurality of images of the first pattern and select an image having a maximum evaluation value, as well as evaluate degrees of focus of a plurality of images of the second pattern and select an image having a maximum evaluation value; and acquire a correspondence relationship between a focal position of an optical system and a control value, based on the control values used in capturing the images of the first pattern and the second pattern, and subject distances of the first pattern and the second pattern.

What is claimed is: 
     
       1. A photographing system comprising:
 a hardware photographing device configured to photograph each of a first pattern and a second pattern provided at a subject distance different from a subject distance of the first pattern a plurality of times at a focal position different for each time; 
 at least one memory storing instructions; and 
 at least one processor configured to execute the instructions to: 
 set, for the hardware photographing device, a control value for changing the focal position; 
 evaluate degrees of focus of a plurality of images of the first pattern photographed by the hardware photographing device and select an image having a maximum evaluation value, as well as evaluate degrees of focus of a plurality of images of the second pattern photographed by the hardware photographing device and select an image having a maximum evaluation value; and 
 acquire a correspondence relationship between a focal position of an optical system and a control value, based on the control values used in capturing the image of the first pattern and the image of the second pattern being selected, and subject distances of the first pattern and the second pattern. 
 
     
     
       2. The photographing system according to  claim 1 , wherein the first pattern and the second pattern are different patterns. 
     
     
       3. The photographing system according to  claim 1 , wherein
 the hardware photographing device includes a liquid lens, and 
 the at least one processor is further configured to set, as the control value, a voltage for changing a curvature of the liquid lens. 
 
     
     
       4. The photographing system according to  claim 1 , wherein, when it is detected that the hardware photographing device photographs the first pattern and the second pattern, the at least one processor is further configured to cause the hardware photographing device to photograph each of the first pattern and the second pattern a plurality of times at a focal position different for each time to acquire the correspondence relationship. 
     
     
       5. The photographing system according to  claim 1 , wherein the at least one processor is further configured to: broadcast, before the hardware photographing device is caused to photograph each of the first pattern and the second pattern a plurality of times at a focal position different for each time, that photographing is to be performed. 
     
     
       6. The photographing system according to  claim 1 , wherein, when the hardware photographing device photographs each of the first pattern and the second pattern, the at least one processor is further configured to broadcast that orientation of the first pattern and the second pattern with respect to the hardware photographing device should be changed, based on each photographed image. 
     
     
       7. The photographing system according to  claim 1 , further comprising a hardware calibration apparatus having the first pattern and the second pattern,
 wherein the first pattern and the second pattern of the calibration apparatus are separated from the hardware photographing device by a subject distance different for each of the patterns. 
 
     
     
       8. A calibration method performed by a computer comprising:
 photographing, by a hardware photographing device, each of a first pattern and a second pattern provided at a subject distance different from a subject distance of the first pattern a plurality of times at a focal position different for each time; 
 setting a control value for causing the hardware photographing device to change the focal position; 
 evaluating degrees of focus of a plurality of images of the first pattern photographed by the hardware photographing device and selecting an image having a maximum evaluation value, as well as evaluating degrees of focus of a plurality of images of the second pattern photographed by the hardware photographing device and selecting an image having a maximum evaluation value; and 
 acquiring a correspondence relationship between a focal position of an optical system and a control value, based on the control values used in capturing the selected image of the first pattern and the selected image of the second pattern, and subject distances of the first pattern and the second pattern. 
 
     
     
       9. A non-transitory computer-readable medium storing a program that causes a computer to execute:
 photographing, by a hardware photographing device, each of a first pattern and a second pattern provided at a subject distance different from a subject distance of the first pattern a plurality of times at a focal position different for each time; 
 setting a control value for causing the hardware photographing device to change the focal position; 
 evaluating degrees of focus of a plurality of images of the first pattern photographed by the hardware photographing device and selecting an image having a maximum evaluation value, as well as evaluating degrees of focus of a plurality of images of the second pattern photographed by the hardware photographing device and selecting an image having a maximum evaluation value; and 
 acquiring a correspondence relationship between a focal position of an optical system and a control value, based on the control values used in capturing the selected image of the first pattern and the selected image of the second pattern, and subject distances of the first pattern and the second pattern.